ceph: fix decoding of client session messages flags

commit ea16567f11018e2f58e72b667b0c803ff92b8153 upstream.

The cephfs kernel client started to show  the message:

 ceph: mds0 session blocklisted

when mounting a filesystem.  This is due to the fact that the session
messages are being incorrectly decoded: the skip needs to take into
account the 'len'.

While there, fixed some whitespaces too.

Cc: stable@vger.kernel.org
Fixes: e1c9788cb397 ("ceph: don't rely on error_string to validate blocklisted session.")
Signed-off-by: Luís Henriques <lhenriques@suse.de>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
index 00c3de177dd66f5eb90451558fcfbf9e7a67a240..1bd3e1bb0fdf0554ad94dddcb604c4680699f7ba 100644 (file)
--- a/fs/ceph/mds_client.c
+++ b/fs/ceph/mds_client.c
@@ -3375,13 +3375,17 @@ static void handle_session(struct ceph_mds_session *session,
        }
 
        if (msg_version >= 5) {
-               u32 flags;
-               /* version >= 4, struct_v, struct_cv, len, metric_spec */
-               ceph_decode_skip_n(&p, end, 2 + sizeof(u32) * 2, bad);
+               u32 flags, len;
+
+               /* version >= 4 */
+               ceph_decode_skip_16(&p, end, bad); /* struct_v, struct_cv */
+               ceph_decode_32_safe(&p, end, len, bad); /* len */
+               ceph_decode_skip_n(&p, end, len, bad); /* metric_spec */
+
                /* version >= 5, flags   */
-                ceph_decode_32_safe(&p, end, flags, bad);
+               ceph_decode_32_safe(&p, end, flags, bad);
                if (flags & CEPH_SESSION_BLOCKLISTED) {
-                       pr_warn("mds%d session blocklisted\n", session->s_mds);
+                       pr_warn("mds%d session blocklisted\n", session->s_mds);
                        blocklisted = true;
                }
        }